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STMicroelectronics L5970ADTR
- Part No.:
- L5970ADTR
- Manufacturer:
- STMicroelectronics
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
L5970ADTR.pdf
- Description:
- IC REG BUCK ADJ 1.5A 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:6,988
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Product details
Overview
L5970ADTR from STMicroelectronics is a 1.5A step-down monolithic switching regulator with internal P-channel DMOS switch (RDS(on) = 200 mΩ typ.), 4.4–36 V input range, adjustable 1.235–35 V output, and fixed 500 kHz switching frequency - used as primary DC-DC converter in automotive battery converters and industrial chargers.
For engineers reviewing the L5970ADTR datasheet, L5970ADTR pinout, L5970ADTR application, or L5970ADTR equivalent, key selection criteria include its 100% duty cycle capability for low-dropout operation, internal 3.3 V reference (±2%), synchronization support for multi-regulator systems, and feedback disconnection protection.
Technical Context
The L5970ADTR implements voltage-mode PWM control with transconductance error amplifier (2.3 mS gm, 57 dB open-loop gain), internal 500 kHz sawtooth oscillator, and dual current limiting: pulse-by-pulse overcurrent detection and frequency foldback during sustained overload. Its P-channel high-side switch eliminates bootstrap capacitor requirements.
It integrates thermal shutdown (150 °C trip, 130 °C hysteresis), INH inhibit logic (0.8 V ON / 2.2 V OFF thresholds), and feedforward compensation via VCC-sensed ramp generation - enabling stable regulation across wide input and load transients without external loop compensation complexity.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Current Limit | 1.8 A max - ensures robust short-circuit protection with pulse-by-pulse current sensing |
| Input Voltage Range | 4.4 V to 36 V - supports direct connection to 5 V bus and 24 V industrial/automotive rails |
| Output Voltage Range | 1.235 V to 35 V - set via external resistor divider on FB pin; 1.235 V internal reference |
| Switching Frequency | 500 kHz fixed - minimizes external inductor/capacitor size; synchronizable externally |
| RDS(on) | 200 mΩ typ. - enables >90% efficiency at 5 VOUT/12 VIN with minimal conduction loss |
| Quiescent Current | 7 mA typ. operating / 100 µA max. standby - supports low-power modes via INH pin |
| Reference Voltage | 3.3 V ±2% - stable, unfiltered internal reference usable for auxiliary circuitry |
Pinout & Package
Package: SO-8 (Small Outline, 8-pin, surface-mount). Thermal resistance Rth(j-amb) = 120 °C/W on standard PCB layout.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 OUT | Regulator output node | High-current path to inductor; connects directly to power switch drain |
| 2 SYNC | Synchronization interface | Configurable master/slave; accepts external clock ≥500 kHz or outputs internal sync signal |
| 3 INH | Inhibit control input | Active-high enable/disable; internal pull-up disables device if left floating |
| 4 COMP | Error amplifier output | Connects to external RC network for loop compensation and stability tuning |
| 5 FB | Feedback input | Resistor-divider junction; regulates output by comparing to 1.235 V internal reference |
| 6 VREF | 3.3 V reference output | Stable, low-noise supply for external circuits; no bypass capacitor required |
| 7 GND | Analog and power ground | Common return for feedback, reference, and control circuitry; must be low-impedance |
| 8 VCC | Unregulated input supply | Power source for internal bias and gate driver; also feeds oscillator ramp generator |
Key Features
| Feature | Design Value |
|---|---|
| Voltage feedforward | Uses VCC to modulate oscillator ramp - improves line transient response without additional components |
| Zero-load operation | Burst-mode functionality enables stable regulation with no output load - critical for standby power systems |
| Feedback disconnect protection | Auto-shutdown if FB pin floats - prevents destructive overvoltage at output during open-divider failure |
| Thermal shutdown with hysteresis | 150 °C trip / 130 °C recovery - avoids oscillatory shutdown during marginal thermal conditions |
| Internal current limit | 1.8 A peak switch current - provides consistent overcurrent protection independent of external sense resistor |
Applications
| Automotive Battery DC-DC Converter | Industrial Charger Control |
|---|---|
Use Scenario: Step-down conversion from 12–24 V vehicle battery to regulated 3.3 V or 5 V for infotainment ECUs. IC Role / Device Role / Timing Role: Primary buck regulator delivering >1 A continuous output with 100% duty cycle capability for cold-crank (4.4 V) support. Use Value: Eliminates need for external bootstrap capacitor and enables reliable start-up during low-battery cranking events. | Use Scenario: Programmable constant-voltage/constant-current charger for sealed lead-acid or LiFePO4 batteries. IC Role / Device Role / Timing Role: Adjustable-output DC-DC stage regulating charging voltage up to 35 V with precision 1.235 V reference. Use Value: Enables single-component solution for multi-cell battery topologies without external DAC or op-amp feedback scaling. |
| STB/DVD Power Supply | XDSL Line Card DC-DC Module |
Use Scenario: Secondary power rail generation in set-top boxes and DVD players requiring low-noise 3.3 V or 1.8 V supplies. IC Role / Device Role / Timing Role: High-efficiency buck converter synchronized to system clock via SYNC pin to reduce EMI. Use Value: 500 kHz fixed frequency + synchronization allows deterministic noise placement and filtering optimization. | Use Scenario: Isolated or non-isolated DC-DC module powering DSL PHY and analog front-end from 12 V or 24 V input. IC Role / Device Role / Timing Role: Compact, thermally robust regulator delivering 1.2–3.3 V at >1 A with integrated thermal shutdown. Use Value: SO-8 package with 120 °C/W Rth(j-amb) supports convection-cooled designs in space-constrained telecom modules. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| L5973ADTR | 2 A switch current, HSOP-8 package, same 500 kHz frequency and reference | Higher output current capability; requires larger footprint and different thermal pad layout | Select when >1.5 A continuous load current or higher peak surge tolerance is required |
| L5970DTR | 1.5 A switch, 250 kHz switching frequency, identical SO-8 package and pinout | Lower switching frequency increases inductor size but reduces EMI and gate drive losses | Select when board-level EMI constraints favor lower frequency or thermal budget permits larger magnetics |
Compared with L5970DTR, the L5970ADTR offers higher switching frequency for smaller passive components, while L5973ADTR provides greater current headroom at the cost of package change - both retain identical control architecture and protection features.
Availability
L5970ADTR is available at Aetrix Electronics and suitable for automotive battery DC-DC converters, industrial battery chargers, and XDSL line card power supplies requiring stable component supply across extended temperature and lifecycle demands.
Supply support for L5970ADTR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing microcontrollers, power ICs, sensors, and analog devices for industrial, automotive, and consumer markets.
The L597x series targets high-reliability, integrated buck regulators for harsh-environment applications - emphasizing internal switch robustness, wide input range, and comprehensive fault protection without external components.
FAQ
What is the minimum input voltage required for L5970ADTR to regulate a 3.3 V output?
The L5970ADTR maintains regulation down to 4.4 V input, enabling full 100% duty cycle operation - essential for automotive cold-crank scenarios where battery voltage drops below 6 V. At 4.4 V input and 3.3 V output, it delivers rated current with verified thermal margin per SO-8 layout guidelines.
Can the L5970ADTR synchronize to an external clock, and what are the timing requirements?
Yes - the SYNC pin accepts external clocks ≥500 kHz with 10–90% duty cycle. When driven above threshold (2.5 VREF), it forces slave mode; when open, it outputs internal sync. Master/slave pairing is automatic when SYNC pins are tied together, with higher-frequency device acting as master.
How does the L5970ADTR protect against feedback loop failure?
If the FB pin becomes disconnected or floats, the internal circuit detects absence of voltage divider bias and forces shutdown within microseconds - preventing uncontrolled output voltage rise toward input rail and protecting downstream loads from overvoltage damage.
Is an external compensation network required for stable operation?
Yes - the COMP pin is the transconductance error amplifier output and must be connected to an external RC network (e.g., 22 nF + 4.7 kΩ) between COMP and FB to ensure phase margin >45° across all operating conditions, as validated in ST's reference design D05IN1530.
L5970ADTR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4.4V
- Voltage - Input (Max):
- 36V
- Voltage - Output (Min/Fixed):
- 1.235V
- Voltage - Output (Max):
- 35V
- Current - Output:
- 1.5A
- Frequency - Switching:
- 500kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
L5970ADTR FAQ
1.How can I place an order for L5970ADTR through Aetrix?
Please submit a Request for Quotation (RFQ) for L5970ADTR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for L5970ADTR reliable?
The price and inventory of L5970ADTR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L5970ADTR is usually 5 days.
3.What payment methods are accepted for L5970ADTR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L5970ADTR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for L5970ADTR?
L5970ADTR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your L5970ADTR order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for L5970ADTR?
For technical support, including L5970ADTR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L5970ADTR requirements.
6.How does Aetrix verify that L5970ADTR is sourced from the original manufacturer or authorized distributors?
All L5970ADTR products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that L5970ADTR meets industry standards.
7.What is the process for return or replacement of L5970ADTR?
All L5970ADTR units undergo pre-shipment inspection (PSI). If there is an issue with L5970ADTR, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The L5970ADTR part is unused and in its original packaging.
Return procedure for L5970ADTR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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